1. Field of the Invention
This invention relates to augers for agricultural mixers, specifically vertical type feed mixers with multiple augers.
2. Background of the Invention
Agricultural mixers are used for mixing feed materials such as hay, silage and other nutrients including animal feed supplements and grains. These feed materials are then discharged and fed to various livestock such as cattle and dairy cows. Sometimes the mixing of such feed materials includes depositing a whole round or square bale of hay into the mixer. The mixer then cuts and processes the bale into the desired consistency before and during the mixing of the other feed nutrients.
In known mixers, there are many different configurations including horizontal augers, reel type arrangements, and vertical augers. In the vertical auger type mixers, the auger designs are generally similar. The auger generally consists of a center core on a vertical axis, with helical auger flighting wrapped around this core. The auger flighting has an overall conical appearance, being wider at the base and narrower at the top. The flighting can also consist of a series of paddles arranged in a spiral pattern. Knives are added to the flighting to help cut and process the feed materials. The wide leading edge of the flighting at the bottom of the mixer is made to travel close to the flat floor of the mixer, scooping or peeling the material upwards onto the flighting. Often a hardened bar (e.g., a grader blade) is added to the leading edge to increase the durability of the auger.
In addition to the leading edge at the base of the auger, the augers sometimes include additional bars, paddles, or sections of fighting around the base. These paddles, sometimes called “kickers” help to move the material being mixed, urging the material in a particular direction. A kicker generally consists of a relatively flat bar or plate which is lower at the front edge than at the rear edge, and can be mounted by itself or in combination with the flighting. The quantity, size, and orientation of the kickers varies depending on the type of materials, type of mixing action, mixing speed, or horsepower consumption desired. These kickers also sometimes utilize a hardened bar at their leading edge to increase the durability of the auger.
The general principle of a vertical mixer auger is to sweep materials onto the leading edge of the lower fighting section, where it is elevated upwards, sliding on top of the fighting sections, to the trailing edge of the upper fighting. As the feed material is carried upwards by the auger fighting, a void is created between the auger fighting and the sidewall of the mixer. The material from above falls downward into this void, causing a continuous boiling action of the material inside the mixer.
Some of the feed material initially swept onto the lower fighting simply flows over and off the back of the lower fighting section. This material remains stationary on the floor of the mixer until the leading edge makes a full revolution. If there is one or more kickers located around the base of the auger, the material is swept up multiple times for every revolution of the auger. Since the kickers do not directly feed the material into the fighting, the effect of these additional sweeping edges is to momentarily lift and move the material in a rotary path around the auger.
Manufacturers of vertical mixers have discovered that by changing the size, angle, and quantity of kickers, they can greatly effect the performance of the augers during mixing. For example, additional kickers at the base of the auger fighting generally increases the rotary action of the materials, and decreases the lifting action of the fighting. By positioning the kickers at an angle pushing material toward the center of the fighting, the lifting action of the flighting is increased, but the rotary action is then reduced. Additional kickers, larger kickers, and more angled kickers typically increase the horsepower required to mix, but can reduce the overall time to complete the mix. The use of additional kickers also tends to help the discharge efficiency during unloading, creating more rotary or sweeping action towards the discharge door.
In known vertical mixers that have at least two augers, the configuration of each of the augers is identical. Thus, the augers were typically designed to be a compromise between mixing efficiency, discharge efficiency, and horsepower. One disadvantage of having identical augers in the same mixer is that the interaction of the feed materials between the augers is limited. It is sometimes observed, for example, that materials in the front auger area stay in the front of the mixing chamber, while materials in the back auger area stay in the back.
Another disadvantage of having identical augers in the same mixer is that the auger nearest the discharge opening cannot be adjusted for a faster cleanout without effecting the performance of the other auger(s). In other words, an auger optimized for mixing the feed is not the best design for discharging the feed.
Another disadvantage of having identical augers is that the augers should be rotated at the same speed for optimal mixing performance. Some drive systems would favor two different rotational speeds if the augers could be made to perform at these different speeds.
Another disadvantage of having identical augers is that the rotational direction of the augers must be the same. Some drive systems, such as a gear drive, would favor rotating the augers in opposite directions.
Another disadvantage of having identical augers is that it can set up a rocking action of the mixer as the feed moves in a predictable motion. This occurs even when the identical augers are rotated out of time from each other. The rocking is a disadvantage because of additional stresses applied to the frame and tongue members, plus potential loss of control while the mixer is being towed.
Another disadvantage of identical augers is that the rocking action created causes inaccuracies in the scale systems used to measure the weight of the feed materials. Accurate measurements of the amounts of feed mixed and discharged are critical to the health and production of both beef and dairy animals.